Imaging of the knee

MR imaging has become the primary imaging modality of the knee. Its advantages include its noninvasive nature, multiplanar imaging capability, excellent soft-tissue contrast, and high resolution. The need for multiple imaging modalities is obviated, as the menisci, cruciate ligaments, synovium, articular cartilage, marrow, and periarticular soft tissues can be simultaneously evaluated. Other imaging modalities may occasionally be helpful in the evaluation of specific problems including CT in tibial plateau fractures, real-time ultrasound for the confirmation of a popliteal cyst or popliteal artery aneurysm, and arthrography for the detection of prosthetic joint loosening.     

Popliteal cysts in adults. Prevalence, associated intraarticular lesions, and results after arthroscopic treatment.

The objective of this prospective study was to determine the prevalence of popliteal cysts and the associated intraarticular lesions in a group of 100 patients scheduled for arthroscopic surgery of the knee and to evaluate the results of arthroscopic treatment for these intraarticular lesions without removal of the cyst. One hundred patients without any knee complaints served as a control group. The diagnosis of a popliteal cyst was made on the basis of ultrasonography. The prevalence of popliteal cysts was 20% in the study group and 0% in the control group. Patients with a popliteal cyst had a significantly higher prevalence of medial meniscal tears (70% versus 19%) and of chondral lesions (85% versus 28%). Tears of the lateral meniscus, however, were more evenly distributed (20% versus 36%). Sixteen of 20 patients with a popliteal cyst were available for a follow-up examination 1 to 3 years after the arthroscopic procedure. Eleven popliteal cysts had persisted. Chondral lesions were the most relevant prognostic factor; all patients with persisting cysts had grade III or grade IV lesions. We conclude that the popliteal cyst is a secondary phenomenon and that treatment should address the underlying intraarticular lesions. In cases of osteoarthritis it may be impossible to treat the chondral lesion successfully in terms of eliminating the effusion.     

The popliteal cyst

A popliteal cyst, originally called Baker’s cyst, is a synovial fluid-filled mass located in the popliteal fossa. The most common synovial popliteal cyst is considered to be a distension of the bursa located beneath the medial head of the gastrocnemius muscle. Usually, in an adult patient, an underlying intra-articular disorder is present. In children, the cyst can be isolated and the knee joint normal. The anatomy, etiopathogenesis, clinical presentation, differential diagnosis, imaging and treatment modalities of the popliteal cyst are presented. The authors try to answer some questions dealing with this condition. Is the cyst isolated, can it be treated as such, is its origin always well-defined and does surgical excision provide a permanent cure?     

Arthroscopy in patients with knee endoprostheses

Remarkable advances have been made in knee replacement. Nevertheless, patients and surgeons still face unsolved problems following implantation of an artificial knee joint. In some cases arthroscopy may serve as a diagnostic or surgical tool. Our experience has shown that arthroscopy is helpful in diagnosing polyethylene wear, fractures of prosthetic components and loosening of the endoprosthesis. Moreover, surgical procedures can be synchronously performed, e.g. lateral release for complete or partial patellar dislocation, parapatellar denervation for retropatellar pain and resection of meniscal remnants or a synovial plica in case of interposed tissue. In contrast to knee infections, early prosthetic infections should be treated with an open procedure.     

Posteromedial compartment cement extrusion after unicompartmental knee arthroplasty treated by arthroscopy: a case report

Unicompartmental knee arthroplasty (UKA) with extrusion of cement into the posterior compartment of the knee is uncommon. Various problems after a UKA procedure, such as aseptic loosening, polyethylene wear and progressive arthritis have been reported. This study will report on a patient with extrusion of cement fragments into the posteromedial compartment of the knee after a UKA procedure. This complication was treated successfully with the direct posterior–posterior triangulation arthroscopic visualization method. In cementing the prosthesis, it is of paramount importance to take caution to completely remove extruded cement remnants in order to prevent this complication during UKA.     

Computerized tomography assessment of femoral and tibial rotation in total knee prosthesis

PURPOSE: CT assessment of the axial deviation of the femoral and tibial prosthetic components in total knee arthroplasty. MATERIAL AND METHODS: January to July 1999, seventeen patients, 10 males and 7 females, mean age 66 years (standard deviation +/- 4) were examined after total knee arthroplasty. Exclusion criteria were prosthesis loosening and severe (equal or superior to 7 degrees) varus or valgus deviation. All patients were examined with knee radiography in the standing position completed by axial projections of patella and by CT scanning. We used a modification of Berger technique and carried out comparative CT scans extended lower limbs and acquisitions perpendicular to the mechanical axis of the knee, from the femoral supracondylar region down to the plane crossing the distal end of the tibial prosthetic component. Reference lines were then drawn electronically on given scanning planes to reckon the axial deviation of the femoral and tibial prosthetic components. RESULTS: Six patients, one female and 5 males, with normal rotational values of femoral and tibial prosthetic components presented no clinical symptoms. Eight patients, 4 females and 4 males, with abnormal values presented the following clinical symptoms: medial impingement, (incomplete) dislocation patella, and lateral instability. One female patient with a normal rotational value of femoral prosthetic component and an altered value of tibial prosthetic component presented medial impingement. Finally two patients, one female and one male, were absolutely asymptomatic although the rotational values of the two prosthetic components were beyond the normal range. CONCLUSIONS: Total knee arthroplasty is presently a standard treatment for many conditions involving this joint. There are several possible postoperative complications, namely fractures, dislocations (a)septic loosening and femoropatellar instability. The latter condition is the most frequent complication among implant failures and is caused by bad orientation of the femoral and tibial components on frontal and axial planes. We measured the orientation of the prosthetic components introducing a CT procedure which modifies the uniarticular with four scans introduced by Berger. The new method uses Berger's parameters and the CT study of both joints by means of Helical CT. With a single examination lasting less than 4 minutes and with the patient in a more comfortable position, we can obtain: 1) comparative and simultaneous assessment of the contralateral joint; 2) several scans to better define Berger's parameters and to accomplish measurement of the rotational deviation with higher precision and markedly decreasing the error margin. The analysis of the results confirms the international literature findings and especially the fundamental importance in positioning both prosthetic components within normal values, as emphasized by the relationship between the clinical symptoms and the rotational degree of the femoral and tibial prosthetic components.     

Severe metallosis following total knee arthroplasty: a case report and review of radiographic signs

Metallosis is an uncommon complication following total knee arthroplasty that leads to osteolysis and implant loosening due to chronic inflammatory reaction. Abrasion between the metallic surfaces of the implant releases metallic debris that interacts with the periprosthetic soft tissues and causes chronic synovitis. Here we present a case of a 65-year-old man who had undergone total knee arthroplasty 10 years ago and developed implant loosening associated with severe metallosis and varus instability. Radiographs show the three typical signs of metallosis: metal-line sign, bubble sign, and cloud sign. This patient was subjected to revision surgery consisting of debridement and primary implant replacement by a hinged endoprosthesis. Knowledge of the typical radiographic and clinical findings of metallosis is important to rapidly diagnose this complication and avoid progressive joint destruction.     

Revision after early aseptic failures in primary total knee arthroplasty

The purpose of this study was to evaluate cases of early aseptic failures presented during the first 5-year follow-up in a group of 981 primary total knee arthroplasty (primary TKA). Predisposing factors as well causes of failures and postoperative complications in different groups of aseptic failures were re-assessed and compared to a control group. A retrospective and cohort study compared one group of 944 primary TKA without surgical revision (890 patients) (Group A) with 22 primary TKA (22 patients) (Group B) that had revision TKA secondary to aseptic failure during the first five years follow-up. The cases of isolated patellar button replacement (n = 8) and infection (n = 7) were not considered in this study. All patients underwent a systematic assessment that included clinical and radiographic examinations, and IKS scores. Aseptic failure was more prevalent at the first 2-year follow-up (63%). TKA loosening (n = 11) and undiagnosed pain (n = 7) were considered the most frequent modes of failures, and laxity (n = 1) was a very rare early cause of failure. The aseptic failure group was characterized as average 5 years younger with a greater number of previous knee surgeries, lower IKS scores improvement, and more postoperative pain compared to control group, despite the fact that the aseptic failure group showed a prevalence of cases during the first 2-year follow-up. Inside this group, the undiagnosed pain group had lower improvement of IKS scores, a remarkable prevalence in prior surgical procedure (71%) and a minor mean interval between primary and revision TKA (11.6 months).     

Fixation of revision TKA: a review of the literature

Purpose  

Early aseptic loosening is a major complication in revision total knee arthroplasty (TKA). It is well accepted that intramedullary stems improve the anchoring of the prosthetic components; however, controversy still exists about the optimal fixation technique of the stems (cementless, hybrid, cemented).     

Causes of failure and etiology of painful primary total knee arthroplasty

The review provides an overview of the causes of failure and the many different aetiologies of a painful primary total knee arthroplasty (TKA). They can be classified into extra- and intraarticular disorders, the latter being divided into biological and mechanical origins. Whereas biological aetiologies like infections have remained stable over time, other causes of failure have changed. In the early times of knee arthroplasty, they were mainly related to technical insufficiencies. A better understanding of knee arthroplasty, patients’ increasing functional demands as well as a continuous development of TKA techniques generated newer problems, which are increasingly related to the functioning of the soft-tissue envelope of the knee. From a therapeutic point of view, three situations can be considered: functional problems not needing reoperations, causes of reoperations not needing an exchange of prosthetic components as well as reoperations with exchange of at least one prosthetic component.     

Arthrodesis of the knee after failed infected total knee arthroplasty

Infection after total knee arthroplasty (TKA) can be a challenging and difficult problem to treat. In selected patients, knee arthrodesis is a well-recognized salvage procedure after infected TKA. The authors retrospectively reviewed their experience with this treatment option, presenting 20 patients (8 women, 12 men), performed between 1990 and 2002. The average age was 67 years (range: 47–81 years) and the mean number of previous surgical procedures was 6 (range: 4–11 procedures). There were multiple indications for knee arthrodesis, including extensive bone or soft tissue loss, poor bone stock, and recurring infections. One-stage fusion was done in 7 knees while, on the other 13, arthrodesis was performed as two-stage fusions. The average clinical follow-up was 4.5 years (range: 2–11 years). 18 of the 20 patients were interviewed and graded using the Visual Analogue Scale (VAS) for pain, the Short Form-36 Health Survey (SF-36), and the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire that has knee-related quality of life items. According to the VAS, the mean intensity was 3.4 points. 6 (33%) of the patients had no difficulty with the knee and 9 (50%) of them had mild or moderate difficulty. The SF-36 scores were similar to those for normative data for patients after TKA, with only the social functioning, role emotional, and physical functioning scores being lower and the role physical and social functioning scores being higher. Three of 20 fusions failed, whereas two knees became non-infected non-unions. In one, the knee infection persisted and required above-knee amputation. The two-stage arthrodesis gave the most predictable rate of fusion. Persistent infection and extensive bone stock losses led to failure even under the best circumstances. In our opinion, arthrodesis of the knee is a satisfactory salvage procedure following a failed TKA, and can provide reliable expectation for a stable, painless extremity for high-functioning patients who are able to walk.     

Double-contrast arthrography in secondary popliteal cysts

The diagnosis of a popliteal cyst is usually made on the basis of a history of discomfort and pain in the medial portion of the popliteal region, together with the finding of a palpable mass in the popliteal fossa. The clinical diagnosis can be confirmed by knee arthrography, if the cyst communicates with the knee joint; in recent years, however, noninvasive US has also become an important diagnostic aid to the radiologist. The S. Anna Hospital (Ferrara) experience is here reported in the diagnosis of symptomatic popliteal cysts, with no valve mechanism at the connection with the joint cavity. Arthrography was performed on 438 patients with popliteal cysts to determine their extent and size in relation to the symptoms and to the presence of underlying knee pathology; only 76 patients from this group were then submitted to surgery. The authors confirm that popliteal cyst is a frequent occasional finding during knee arthrography which almost completely lacks any clinical relevance in most cases. Moreover, taking arthrographic findings as a starting point, the authors describe the different anatomotopographic patterns of popliteal cysts.     

Demonstration of an infected popliteal (Baker's) cyst with three-phase skeletal scintigraphy

A case is reported of an infected popliteal (Baker's) cyst demonstrated with triple phase skeletal scintigraphy. Although double-contrast arthrography and ultrasonography are currently the modalities most frequently employed to diagnose the presence of popliteal cysts, they may also be detected utilizing this radionuclide technique in the course of evaluation for knee joint disease or septic arthritis. Radionuclide studies may be more sensitive for the evaluation of associated inflammatory disease involving the knee joint.     

Popliteal cysts: a reassessment using magnetic resonance imaging

The advent of magnetic resonance imaging (MRI) prompted the reevaluation of the incidence of popliteal cyst and its associated injuries. We reviewed more than 1000 consecutive MRI examinations of the knee performed on patients referred for evaluation of internal derangement. We report a 5% incidence of popliteal cyst, which is lower than has previously been determined. We believe that the reported higher incidence was due to arthrographic distention of normal, collapsed bursae. The strong association between popliteal cyst and tear of the medial meniscus is confirmed. We report for the first time to our knowledge the 13% association between popliteal cyst and complete tear of the anterior cruciate ligament.     

Is previous knee arthroscopy related to worse results in primary total knee arthroplasty?

According to literature, knee arthroscopy is a minimal invasive surgery performed for minor surgical trauma, reduced morbidity and shortens the hospitalization period. Therefore, this type of surgery before total knee arthroplasty (TKA) could be considered a minor procedure with minimum postoperative complication. A retrospective and cohort series of 1,474 primary TKA was performed with re-assessment after a minimum follow-up period of 2 years: 1,119 primary TKA had no previous surgery (group A) and 60 primary TKA had arthroscopic debridement (group B). All the patients underwent a clinical and radiological evaluation as well as IKS scores. Statistical analysis of postoperative complications revealed that group B had a higher postoperative complication rate (P < 0.01). In this group, 30% of local complications were re-operated and 8.3% of these cases underwent revision TKA (P < 0.01). The mean interval between arthroscopy and primary TKA was 53 months. However, statistical analysis did not reveal a direct correlation between arthroscopy/primary TKA interval and postoperative complications/failures (P = 0.55). The Kaplan–Meier survival curves showed a survival rate of 98.1 and 86.8% at 10 years follow-up for groups A and B, respectively. Our data allow us to conclude that previous knee arthroscopy should be considered a factor related to postoperative primary TKA outcomes as demonstrated by the higher rate of postoperative complications and failures (P < 0.001) as well as a worse survival curve than group A.     

Deep posterior knee pain caused by a ganglion of the popliteus tendon — a case report

The most common causes of posterior and posterolateral knee pain (besides referred pain) are knee joint effusions, tendinitis of the hamstring tendons, Baker cyst (semimembranous cyst), bursitis, meniscal pathologies such as tears and ganglions and lesions of the anterior cruciate ligament. Less common causes include popliteus and gastrocnemius tendinitis, arthrofibrosis after trauma. posterior cruciate ligament sprains. deep venous thrombosis and/or irritations of the common peroneal nerve. We present one patient with posterolateral knee pain after a minor contusion. Magnetic resonance imaging revealed a degenerated posterfor horn of the lateral meniscus and a somewhat unclear polypoid structure in the intercondylar region. As the posterior component of the pain persisted even after an arthroscopic partial meniscectomy, an operative revision was performed. A small ganglion of the sheath of the popliteus tendon was found and excised. The patient was immediately relieved of his pain after this procedure. To our knowledge this is the first report concerning a ganglion of the sheath of the popliteus tendon causing posterior knee pain. A similar pathology of the popliteus tendon has been described earlier but at a different localisation (in the hiatus), simulating a parameniscal cyst.No benefits in any form have been received from a commercial party related directly or indirectly to the subject of this article. This work has been presented at the Annual Meeting of the Swiss Orthopedic Society in Geneva 1995 It won the second poster prize     

Predisposing factors which are relevant for the clinical outcome after revision total knee arthroplasty

Purpose

The objective of this study was to investigate the outcome of revision total knee arthroplasty (TKA) in relation to the cause of index failure, the characteristics of the index procedure, and the elapsed time between index TKA and revision.

Methods

A retrospective review based on a prospective database was performed on 146 consecutive revision TKA’s. Variables tested were the cause of index failure; the elapsed time between the index and revision procedure; patient age at time of revision; partial or total revision of the implants; the performance of a tibial tubercle osteotomy; the presence of radiolucent lines; postoperative patellar tracking; and coronal plane alignment. Outcomes were measured with the Knee Society Knee Score (KS), Function Score (FS), and X-ray evaluation.

Results

Mean KS improved from 27.6 (SD 21.6) to 71.5 (SD 24.2) after revision (P?<?0.0001), mean FS from 27.5 (SD 22.7) to 53.3 (SD27.7), P?<?0.0001. Overall survival rate was 90% at 5?years and 85% at 10 and 14?years. The cause of index failure had no significant influence on any of the outcome parameters. Significantly, better outcomes were noted for partial revisions and for revisions in older patients. Early revisions (<2?years) were mostly performed for infection and instability, whereas late revisions (>2?years) were mostly performed for polyethylene wear and loosening. The survival rate for late revisions was significantly better than for early revisions (P?=?0.002).

Conclusion

Revision TKA leads to a significant reduction in symptoms and improvement in function. The worst results can be expected for early revisions in young patients. Revision TKA is a demanding procedure with variable results and should therefore be performed by experienced surgeons.

Level of evidence

Therapeutic study—Level IV.     

Short-interval two-stage approach to primary total knee arthroplasty for acutely septic osteoarthritic knees

Treatment strategies for advanced knee osteoarthritis with coexistent joint infection are not well established. While in periprosthetic joint infection the two-stage approach has been studied extensively, only few case reports on two-stage total knee arthroplasty (TKA) for knee osteoarthritis with coexistent joint infection have been published. The purpose of this paper was to report on our method of implementing a two-stage TKA with intervening antibiotic-loaded articulating cement spacers and a short interval between first- and second-stage procedures to treat two patients with Staphylococcus aureus-infected end-stage knee osteoarthritis. Consistent infection eradication was found at a 1-year follow-up with postoperative range of motion and knee scores comparing favourably with those of other case series. Level of evidence V.     

TKA outcomes after prior bone and soft tissue knee surgery

Purpose

Bone surgery around the knee joint could represent a more traumatic prior surgical procedure compared to soft tissue knee surgery and may predispose to differing postoperative total knee arthroplasty (TKA) outcomes. The objective of this study was to analyse the postoperative results as well as complications and failures in two groups of patients that had undergone knee surgery prior to primary TKA (bone surgery and soft tissue surgery) when compared to the no prior surgery group.

Methods

A retrospective and cohort series of 1,474 primary TKA were evaluated at minimum follow-up period of 2 years: 1,119 primary TKA underwent no prior surgery (1,119 patients) (group A), 85 primary TKA (85 patients) (group B) had prior bone procedure [high tibial osteotomy (n = 64), tibial plateau fracture (n = 10) and patellar realignment (n = 11)], and third group of 146 primary TKA (146 patients) (group C) had undergone a soft tissue procedure [arthroscopy (n = 60) and menisectomy (n = 86)] before primary TKA. All the patients underwent a clinical and radiological evaluation as well as International Knee Society (IKS) scores.

Results

Preoperatively, group B had 40 % of cases classified as stage IV knee arthritis (p < 0.02); while 57 % of cases in group A showed higher levels of knee malalignment (p = 0.001) and group C had lower BMI (p = 0.001). Intraoperative complications revealed no difference. Although group B had the poorest postoperative mean values of knee flexion, TKA procedure improved the preoperative mean values of knee flexion in all the study groups. The postoperative complications were more prevalent in group C (p < 0.001), while the percentage of revision TKA was similar for all study groups (p = 0.5). At 120-month follow-up, the Kaplan–Meier survival curve rates showed no difference (p = 0.29).

Conclusion

This study confirms that prior knee surgery could be considered a clinical condition predisposed to higher postoperative complication rate in primary TKA compared to the no prior surgery group. After analysing the three study groups, group C showed a higher rate of postoperative local complications and lower IKS knee scores, while the group B showed the poorest postoperative mean values of knee flexion as well as the need for extended surgical approach (TTO approach) was more prevalent in this study group. However, statistical analysis did not reveal a direct correlation between the type of prior knee surgery and TKA failures.

Level of evidence

IV.     

后稳定型人工全膝关节初次置换术后患者满意度调查

 目的 调查后稳定型人工全膝关节初次置换术后患者的总体满意度。方法 选择行后稳定型人工全膝关节初次置换术患者1465例, 术后1年给纳入研究的患者邮寄一份由笔者设计并验证的膝关节置换术满意度量表, 其中包含对手术的总体满意度和对具体功能或症状缓解程度的15个分项满意度。收集患者作答后的量表并统计分析。结果 1173例患者(1588例膝关节置换)寄回了量表, 总体满意度为87.3%, 最不满意的6个分项为盘腿坐(不满意率55.2%)、下蹲(52.1%)、快走或慢跑(45.2%)、膝关节活动时有响声(34.6%)、膝关节感觉不自然(31.4%)和爬楼(28.7%)。结论 后稳定型人工全膝关节初次置换术满意度较高, 术后1年WOMAC疼痛分值对满意度有显著影响。